main.cpp

易学c++源码

#include "iostream.h"
#include "stdlib.h"
void main()
{
	float a,b,c,temp;
	char oper1,oper2;
	cout <<"请输入一个表达式（eg.1+2*3）：" <<endl;
	cin >>a >>oper1 >>b >>oper2 >>c;
	if ((oper2=='*' || oper2=='/') && (oper1!='*' && oper1!='/')) 
	{
		switch (oper2)
		{
		case '*':
			{
				temp=b*c;
				break;
			}
		case '/':
			{
				if (c!=0) temp=b/c;
				else 
				{
					cout <<"出错啦！"<<endl;
					exit(1);
				}
				break;
			}
		default:
			cout <<"出错啦！"<<endl;
			exit(1);
		}
		switch (oper1)
			{
			case '+':
				{
					temp=a+temp;
					break;
				}
			case '-':
				{
					temp=a-temp;
					break;
				}
			default:
				cout <<"出错啦！"<<endl;
				exit(1);
			}
	}
	else
	{
			switch (oper1)
			{
			case '+':
				{
					temp=a+b;
					break;
				}
			case '-':
				{
					temp=a-b;
					break;
				}
			case '*':
				{
					temp=a*b;
					break;
				}
			case '/':
				{
					if (b!=0) temp=a/b;
					else 
					{
						cout <<"出错啦！"<<endl;
						exit(1);
					}
					break;
				}
			default:
				cout <<"出错啦！"<<endl;
				exit(1);
			}
			switch (oper2)
			{
			case '+':
				{
					temp=temp+c;
					break;
				}
			case '-':
				{
					temp=temp-c;
					break;
				}
			case '*':
				{
					temp=temp*c;
					break;
				}
			case '/':
				{
					if (c!=0) temp=temp/c;
					else 
					{
						cout <<"出错啦！"<<endl;
						exit(1);
					}
					break;
				}
			default:
				cout <<"出错啦！"<<endl;
				exit(1);
			}
	}
	cout <<a <<oper1 <<b <<oper2 <<c <<'=' <<temp <<endl;
}